1. Field of the Invention
This invention relates to a disc cartridge, and more particularly to a disc cartridge which is adapted to rotatably receive a hard disc, particularly, a magnetic disc therein.
2. Description of the Prior Art
Conventionally, a tray system or a cartridge system using a casing has been generally employed for protecting a compact disc or a video disc used for a digital-data storing unit, a video unit, a video camera or the like from damage and dust to ensure its safety in both non-use and use. For this purpose, the casing is provided with a slidable shutter made of metal which is operated to close a head inserting hole formed at the casing in non-use and open it in use.
Such a shutter is generally formed of a metal plate into a substantially U-shape and is slidably fitted on the casing so as to slide on upper and lower surfaces of the casing. For this purpose, upper and lower surfaces of a slide area section of the casing on which upper and lower shutter plates of the shutter fitted are formed in a manner to be flat and parallel to each other for ensuring smooth sliding operation of the shutter. In order to prevent a distal opening of the shutter, defined between distal ends of the shutter plates, from being enlarged during fitting of the shutter on the slide area section of the casing to cause the shutter to be disengaged or separated from the casing when dropping the cartridge or to cause the cartridge to be below the standards, it has been attempted to have the distal opening of the shutter formed into a reduced width in advance, to thereby forcibly render both surfaces of the shutter parallel to the upper and lower-surfaces of the casing the shutter is fitted on the casing.
Unfortunately, such an attempt fails to render both plates of the shutter, which have been fitted on the casing, parallel to the slide area of the casing, resulting in the distal ends of the shutter plates being pressedly contacted with both surfaces of the slide area section of the casing. Also, a variation of precision of the components of the disc cartridge such as the shutter, the casing and the like during the manufacturing or an inadequate combination therebetween often leads to an inconvenience such as a failure in smooth sliding of the shutter on the casing, pressing of the shutter against the casing, shaving or cutting of the casing by the shutter, drop-out of an information from a disc due to adhesion of the shavings to the disc, or the like.
Accordingly, it would be highly desirable to develop a disc cartridge which is capable of ensuring smooth sliding operation of a shutter on a casing while eliminating disadvantages such as shaving or cutting of the casing by the shutter, drop-out of information from a disc, release or separation of the shutter from the casing, and the like.